Pneumatic container and method and apparatus for making same



Aug. 24, 1965 E. P. HARRIS 3,201,929

PNEUMATIC CONTAINER AND METHOD AND APPARATUS FOR MAKING SAME Original Filed June 19, 1957 3 Sheets-Sheet 1 INVENTOR. [DWARD P/l/IRB/J Aug. 24, 1965 E. P. HARRIS 3,201,929

PNEUMATIC CONTAINER AND METHOD AND APPARATUS FOR MAKING SAME Original Filed June 19, 1957 3 Sheets-Sheet 2 8 INVENTOR. 044 450 12 HARRIS fl/5 AIME/Vi) 3 Sheets-Sheet 5 INVENTOR.

[DAM/5'0 I. flARR/J BY E HIS Aim/Mi) g- 1965 E. P. HARRIS PNEUMATIC CONTAINER AND METHOD AND APPARATUS FOR MAKING SAME Original Filed June 19, 1957 United States Patent This invention relates to air bags and is particularly concerned with the structure of said air bags and the methods and apparatus used in the manufacture thereof.

The present invention is a division of Patent No. 3,033,- 557 filed June 19, 1957.

It is an object of this invention to provide a new and improved air bag free from. seams or joints whereby the bag is increased in strength and the tendency toward rupture, upon flexing of the bag, is greatly reduced.

In carrying out the above object, it is a further object to more perfectly balance an air bag whereby heavy portions at the periphery thereof are eliminated through the elimination of seams and joints.

Another object of the invention is to provide a method for making an air bag wherein one or more of a plurality of layers of curable elastomeric material may be extruded and wherein cord reinforcements are wound on at least two of said layers and interposed between said layers in criss-cross relation without laps whereby the entire structure may be expanded and subsequently vulcanized to form an air bag of the desired size and shape.

A further object of the invention is to provide a positioning comb for guiding the cords which make up the reinforcing layers in the air bag, the comb being capable of passing knots in the cords without, in any way, reduc ing the efiiciency of the comb to align the cords.

Air bags have many uses, the most common of which are concerned with air springs wherein bags having one or more convolutions are used, vehicular tires and similar annular-shaped objects. The methods for making these bags are varied wherein certain of the bags are made in tubular form on a mandrel from strips wrapped therearound, the resulting tube being expanded and shaped while others, such as vehicular tires, are built up on mandrels from strips to the desired size. In this instance, the joints in the strips cause the tire to be thickened at certain positions which throws the tire out of balance and makes the tire bumpy when in use. When the bags are used for air springs, the joints, due to the flexing of 'the bag, tend to weaken and establish points of failure.

A bag for an air spring together with a method for making the same is clearly shown in Brown Patent 2,208,- 540 wherein a tube made up of lapped strips, wherein the fabric is incorporated within the rubber-like material, is placed in a mold and is expanded and cured therein in the desired shape. The Brown patent shows a twoconvolution bag wherein beads or reinforcing wires are present in opposite ends thereof. It is apparent that bags of this character may be formed in a similar manner 1 wherein only one convolution or more than two convolutions are desired.

My invention is specifically directed to an air bag which may be used as a spring, tire or for any other desired use wherein the air bag is formed from a tubular member which is later expanded and shaped to the desired form and is then cured. The tubular member is preferably manufactured from extruded, curable material wherein the cords are wound therein whereby the finished article is devoid of laps and seams and is, therefore, wellbalanced and highly resistant toward failure during flexmg.

conditions.

3,201,929 Patented Aug. 24, 1965 "ice The continuous tube free from laps or joints as made by the present invention may be subsequently formed into an air bag for use as a tire, spring, etc., in the same manner and in similar apparatus to that shown in the Brown patent aforementioned, and this forming or expanding operation is not a part of this invention which is directed specifically to a method for making the tubular member that is to be expanded and to the article subsequently formed which is completely free of laps and unbalanced portions whereby greater uniformity in the air bag is obtained and wherein the strength and rupture-resistant qualities thereof are greatly enhanced.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

FIGURE 1 is a view showing one form of apparatus used to make tubular members to be subsequently formed into air bags.

FIGURE 2 is a modification of one stage of the apparatus of FIGURE 1 showing the application of an inner liner for the tube.

FIGURE 3 is a fragmentary enlarged view of the comb used in connection with the cords applied to the tubing and is taken in the direction of the arrow marked 3 in FIGURE 1.

FIGURE 4 is a partial sectional View of the comb shown in FIGURE 3, taken on line 4-4 of FIGURE 3.

FIGURE 5 is a fragmentary diagrammatic section of the comb showing the displacement of one comb member relative to the other.

FIGURE 6 is an enlarged view of one of the cord spools showing the tensioning means and the guiding means.

FIGURE 7 is a partial sectional view of a length of tubing showing the various layers in their proper relationship.

FIGURE 8 is a sectional view taken on line 88 of FIGURE 7 showing a cross section of the tube.

FIGURE 9 is a view of the tube shown in FIGURE 7 expanded into the form of an air bag.

The use of air bags, particularly as air springs in suspension systems of vehicles, is becoming more important as speed of travel increases. This may be explained by the fact that when vehicles, such as automobiles, busses, railway cars, etc., travel around curves at high rates of speed, there is a tendency for the vehicle to dip and sway giving an unpleasant sensation to the riders. By the use of air suspension systems, it is possible to feed air into springs at one side of the vehicle and bleed air out of the springs at the other side of the vehicle as it travels around a curve and thus maintain a more or less even keel under any and all conditions of road travel.

Another feature which is available when air springs are used in vehicles is the levelizing action of the springs. That is to say, each vehicle is designed to have a definite road clearance and if this road clearance is maintained uniform, the center of gravity of the vehicle is maintained at a set position whereby the vehicle rides better under all When using conventional coil or elliptical springs, the vehicle settles as the load increases and, furthermore, the spring rate changes markedly. Thus, when the vehicle is empty, its road clearance is greatly increased over the clearance available when the vehicle is full or overloaded. These variables may be eliminated completely when using an air spring suspension since through the use of levelizing systems, the road clearance of the vehicle is maintained constant regardless of the road conditions, thus making for a better ride. Furthermore, the spring rate of an air spring is more constant under varying loads than is the spring rate of a coil or elliptical spring. Thus,

the air "spring formed from one or more air bagsor from a single air bag having one or more convolutions is highly V desirable in modern vehicular suspension'sys terns. These bags are forined from multi-p'ly rubber-like material-reinforced withlcords and these bags, inthe past,

have been formedin much the" same-manner as used in forming a tire wherein plys of rubber-like material' with hancedby the fact that'eachspool SO-is provided with a tension device'so that the cordbeing drawn therefromis underuniform tension This is shown-in FIGURE 6 wherein the spool 30 is carried by a, spindle 50 which is mounted on the disc 28. Between the spool 30 and a backplate 52is aspring member 54 which drags on the spool to 7 provide the degree of tension desired. The cord 31 comin'g' off the spool passes'throughseveral hooks 56, 58'and and withoutcords embedded therein are built up on Ia mandrel into a tubular form a'sdisclosed in the aforementionediBrown patent and are then expanded'and cured intthe desiredshape. I Since theiinitia'l tube is made'up of sheets of different'typesof-m'aterial; necessarily'the tube includes aplurality of hips and scams. These'laps'form thickened'portions in the finished product making -for non'-,

uniformity in cross section and likewisethe laps and'se'ams t sometimes produce points :ofifailurefupon flexing {of the bag. It is quiteapparenttthat the laps,-for example,in an 'autornotivetire', create points of unbalance in the the due to the additional material present. "Inany event,':itis

highly desirable to produce arrair: bag free. from laps regardless of its end use since such a bag will be'more uniform in 'cross section, have :fewer points susceptible to failure, betbetter balanced and,lin:general, be a more usefularticle. The present inventionfis specifically directed to ani'air bag- .of this char'acterland to the method for; forming'such an air bag wherein'atleast the inner or outer;- surface and the cord reinforcing portioxisath'rebfare free from laps; joint'sfo'r seams; up it a t v ,7

Referring specifically to the-drawings, FIGURE .1 shows diagrammatically an apparatus whiCbmaybe used in the formation of tubing which may besubsequeritlyvforined into-air bags; The, apparatus -shown"at" comprises 'a- 60 whereupon it i's-directed totlthe comb. 44. :The specific design of the spool, the tensioning deviceand the feeding I .cement .is pumped through ductsf64,and excess cement passes through exit: ducts. 66 to a supply'means wherein it"is recirculated through the'boi 62.. A wiper 68 is provided atthe .exit'of'tliebox' for wiping excess cement off the cords and the wiper 63' merely comprises a resilient plate such' ass a plate made from Teflon or nylon which rubsagainst the cords for removing the lexcessicement which then flows' back through thelduot 66 for reuse.

tuber '70 whereupon a second layer 72 of uncured rubberlike'm'aterial-is' tubfed jonto the surface of thecord layer.

cross headtuber 22 throu'g'h which is passed a mandrel'2'4. I

At the exit end of the tuber, 22 the mandrel, Whichis .properly treated at the :surface thereof; includes a tubular, 7

covering 26 of uncured rubber-like'fmat'erial Thefrnandrel then passes through an apertured rotatin'g'disc'28 which carries a plurality of suitably" disposed spools '30 each carrying a supply of cord; for example,'a nylon cord;

' The-disc 28 is .driventhrough achain drive'32 from a drive shaft 34 that is rotated by a motorfifi which includes} a suitable speed reducer 38 therewith. The mandrel r24 is positivelymoved toward the-right;of; the apparatus "at a constant rateof; speed. I One way'to accomplishj'this isto F In this instance; the second layer may alsojtbe applied int strip form 'fr'om' a ree'l74'as shown in'LFIGURE 2. In- 'this instance, the second'layer comprises a longitudinally extending sheet I or strip 760i 7 uncured rubberlike 'rnaterial which p asses throughfa'funne'l-like' device mama wrapsait around thefcord layer on themo'ving ":rnandre1t24; The second layer '72 may belapped or butt- -jointed, preferably the latter} The mandreli24 with therubber-likelayer 72 thereon znextpasses through {a second disc' 80 driven by the same "type; of 'driving means us'ed iwith the 'first'disc '28; The

disc 80 also includes aflplurality of spools positioned aroundlthe outer periphery {thereof and includes a secnd 1 2 5 81 'whioh i s' siniilar in alijres'peic-ts'tothe comb t '44. Theionly: differencefwith'respect to discs 28 and f #80 resides in the fact that the disc 80 rotates in a diattacha cable at the opposite-endof the mandrelwhich is woundrup on a reel 42Lat-the opposite 'end' of the drive I shaft '34. j Thus, the movement of themandrel' is syn- V chronized with the speed of rotation of the disc 28;fT-he disc 28 includestany suitable number ofspools,-30;-,and this is best determined by the diameter of the cord totbe "used andthe diameter of the-extruded tubular coveringz26 r on themandrel. Preferably, a sufficient number of'cords Jection opposite to the disc '28 whereby the cord layer superimposed upon the ifubber-likeilayer. 7-2 is wrapped in a; criss-cross fashion withrespectto t-hefirst cord layer.

" Here again the' a'n'gle 9f wrapp'ijig is between 5 and are applied to the surfacetto substantially coverthe sur L faceand these cords are woundonto the surface at an angle of between 5 and :30-to the axis'of the mandrel, preferably atabout 15. The angle iscontrolledbyithe a xial travel ofthe mandrel: and bythe comb 44' adjacent the center of fthe disc 28 which comb will be explained in detail hereinafter. Itis apparent that the cords must; all

terialvis' .120 inch thick, seventy-two' two-ply cordsare p30 and preferably 'about 15 Thusflhetwo cord layers are wrapped in opposite i directions at 'the same angle from the axis of-the -mandrel24h In this instance, a

1 'thre e-ply nylon cord is u-sed having a' normal'diameter. of .027 inch. This l'arg'er'diameter cord takes care of the increased diameter, of the ltube'. Oft course mo're spools couldbe added and a two.ply.t 'cord used to ac- V -oornplish the same result Also, if'thecords arenot laid contiguous but allowed to be spaced,fthis adjustmerit-isnot necessary. 'Aftcr the second. cord layer is wrapped onto the rubber-likelayer 72, the mandre1-24, be fastened tothe surface of the layer '26 on the mandrel at the start of the operation butvonce lthe operation-is 'coma mencedtheiapplica'tionof the cords is continuoussojlong, as the supplyof cord'material' is maintained ori the spo'ols. v As a specific example, on a mandrel 2% Qinche'suin'di-.

jarne ter whereimthe first layer offtubed irubberrlikef nae' with its associatedflayersplthereon passes through a third tuber T90 which; tubes. a layer 92 :of 7 uncured; rubber-like nlay also 'be appli'e'dfby wrapping iffide-sired. i This 'then forms 'the' firiished' uncured tubing ,zassembly which lma terial over the secondfapplied'cord layer. This layer {comprises threeilayers of uncured rubber like material havinginterpg'sed 'therebetween layers of cord wrapped wound onto the' tube whereby the cords are disposed'ima layer only one cord thick which substantially cover the entire surface of thetube." I The-cords each' have' a'normal diameter of .022 inch, Since-the'disc'28 is rotating in this 1 instance at l r-.p.m ;*and the-mandrel is travelling at-airate.

'of'twenty-eightinches per revolution, the 'icords are laid ontojthejsu'rface :of the tube layer 26 in'a uniformmaritner and aIe'partiaIly'embedde'dthereim This eifeet isea fin opposite direct-ion (the cordsgone'wit h respect tojthejother.- t. t

Tilt is funderstoodjthat a gsecondfleeme'ntibox 'siinilar to "the. box "62] m-ayfb sed after -.the wrapping of the seethis i s l g nerially preferable since a so as .to form amiss-crossing of 'ond" cord ayes an betterbondi isiobtained betwenfthe rubber-like mate- 'rial and :cord s; if the cerrieri-tis applied-to the cords. Similarly,- pressure;rollersi inotj shown, may be used after 7 The mandreh-g'with thecement-coated cordsv thereon, then passes throughi'a second cross head to a degree in the uncured rubber surface upon which they are wound.

It is further understood that if third and fourth cord layers are desired, the plys may be built up in the same manner as those disclosed through the use of additional winding dis-cs and tubers.

It is also manifest that in place of a continuous machine, the lengths of the mandrel may be removed and passed through separated tubers providing the ends of the cord are bound so as to prevent unraveling. All of these modifications are contemplated.

After the finished tubing is made by the method disclosed, the mandrel, which is preferably formed of a plurality of pieces of specific lengths joined together, is broken and the tubing is cut so that each length of mandrel supports a similar length of tubing. The tubing is then slipped off the treated surface of the mandrel and cut into lengths compatible with the curing mold to be used and the tubing is pressure-formed and cured in the mold. In this connection, the application of a wire bead as shown at 100 in FIGURE 9 is carried out in a conventional manner wherein, if a wide-mouth opening is desired as shown, the tube is flared to the desired diameter prior to being placed in the curing mold whereupon the bead and tube are held while the re mainder of the bellows of an air bag is pressure-formed and cured within the mold.

In place of the second app-lied rubber-like layer 72, it is possible to form the second layer by application of a plurality of coatings of cementitious material. This method is useful in some instances whereby the intermediate rubber-like layer is built up from rubber-like material dissolved in a suitable solvent which is applied and evaporated until a layer of a desired thickness is obtained.

Referring specifically to FIGURES 3, 4 and 5, a section of the comb used with the cord winding discs is shown in detail. This comb comprises a flanged apertured tube 110 which is bolted by means of bolts 112 to the disc 28 or 80 as the case may be. The tubular portion 110 extends outwardly of the disc, surrounds the mandrel and supports, adjacent its outer end, an annular rubber block 114 over which the cords pass. The block 114 has at its outer end a pair of comb members 116 and 118. These comb members provide a plurali-ty of teeth which are held spaced by spacer 1 26 and which are held in relative radial position to one another and to the member 11$) by a disc 122 bolted to the member 110 by bolts 124. When the bolts 124 are loosened, the two comb members 116 and 118 are rotatable with respect to one another so that the tooth position of one comb relative to the other comb may be varied. In this instance, the width of the spaces between the teeth is at least twice the diameter of the cord to be used while the lateral spacing between the two comb members is at least four times the diameter of the cord to be used. This particular spacing is used to permit knots in the cord to pass therethrough. It has been found that where a single cord is used and the cord on the spools includes knots, each time a knot comes to the conventional comb, the cord breaks and requires shutting down of the machine. The present comb, due to the Wide spacing between the teeth, permits the knots to pass there-through. When nylon cords are used, the knots must be of a special character to prevent slipping and, in this instance, the knots present a diameter of about four times the diameter of the cord and, of course,

where nylon cords are used, the spaces between the teeth on each comb should not be less than four times the diameter of the cord, these factors being determined for the specific cord being used. Since the spacing between the comb teeth is greater in all instances than the diameter of the cord and, since the cords are generally laid onto the mandrel at an angle, it is necessary to orient the two comb members to prevent the cords from going onto the mandrel in pairs. These comb members are spaced radially with respect to one another as shown in FIGURE 5 wherein the distance between the center lines of the teeth or, for that matter, between the edge or adjacent teeth, is shown at A, and is equal to the product of the tangent of the angle on which the cords are to be wrapped and the distance between the comb members or the tangent of angle at times b. When the combs are displaced radially in this manner, the cords will always rub, as shown in FIGURE 3, against opposite sides of the teeth whereby they are properly guided as they are laid upon the rubber-like layer on the mandrel.

The finished tube is shown in FIGURES 7 and 8 at 139 wherein the outer layer 92 covers a second cord layer 91 which is laid upon the second rubber-like layer 72 which, in turn, covers the first cord layer 33 which is laid upon the first rubber-like layer 26. This forms what may be termed a two-ply tube wherein the cord layers 33 and 91 are cries-crossed from one another. When the tube is expanded to form the air bag, these cord layers expand and move to form a lattice-like reinforcing structure which, when the material of the formed bag is cured, become integrated with the remainder of the bag for reinforcing the same.

It is apparent that since the bag contains no laps in the cord layers, the strength of the bag is greatly increased over lap-type structures and similarly, the possibility of rupture of the bag is greatly decreased since there are no joints or seams in the reinforcement which might weaken the bags. In this connection, therefore, at no point in the present air bag structure is there more than two layers of cord as diiferentiated from the usual lapped type of structure wherein there are four cord layers in the seams to form thick joints which weaken upon continued flexing and creates points of rupture.

It is manifest that tubes of this character may be formed into tires by practicing the same procedures as used in the manufacture of air bags, the only difference being that the mold is of slightly difierent shape and wire beads are used at opposite sides of the tube.

'In the present instance, a finished tube 2.240 inches in outer diameter and having an ID. of 2, inches is formed into an air bag having a maximum outside diameter of seven and one-half inches. Obviously, other bags may be formed from the same diameter tubing although they will vary in strength and deflection characteristics over the present bag and, in all cases, it is best to arrive at the desired thickness and structure of the starting tubing by trial of the finished product.

The rubber-like material used in the manufacture of these bags may be any suitable vulcanizable material such as compounded natural rubber, compounded butacliene styrene copolymer rubber, compounded butadiene acrylonitrile copolymer rubber, compounded polychloroprene, etc., or compatible mixtures of any of the above, etc., wherein the compound is similiar to the usual grade of tire stock. The specific formulation of the rubberlike compounds form no part of this invention, it merely being necessary to have uncured material which is capable of being subsequently vulcanized or cured and which is compounded to provide the desired strength, flexibility and hardness. Since all of these factors are controlled by well known expedients, further elaboration thereon is not believed necessary.

The term nylon as used herein is the tradename for a super polyarnide such -as the reaction productv of di-s,

amine and-a, po1ybasic,acid','etc.' This material and the reactions used in its .manuf'act'ure is. 'clearlyQdisclosed inIC'arothers Patents'2,130,-947, 2,130,948 and 2,139,523,

for example. ethylene.

While the Teflon is -a tradenarne for polytetrafiuorounderstood that other forms might bea-dopted,

.7 What is claimed is as follows;

, 1. A positioning, comb for aligning; and supplying a, plurality of moving filaments in parallel relation to a embodimentsiof the present invention as hereindi-sclos'ed constitute 'prefe r r'edformaeitis-to be 8 8.1 1 Ill-positioning comb fonapplyinga plurality of filamerits in closelysp'aced position to a'moving mandrel ate-afpredetermined angle out of parallel withjtlie :axis

of" the mandrel, the combination; comprising; acircular comb memberfhaving ,a plurality of"radially equally spaced teeth ftherearound wherein the spacing between subsequent. operation wherein each filament, is .fed from a :source capable of providing an indeterminate. length of. the filament, the-combination comprising; a first comb member; including a plurality of equally spaced teeth therealong the spacing between each tooth being equal to at least twice the diameter of t he filament, a second,

comb member dimensionally similar to, the, first man; ber. and'disposed in'spaced coaxial relation. to the first so that the teeth of the first comb member, are-displaced 20, member and positioned transversely with respect thereto: a

from the-teeth of the second comb member afdistance- I equal to the product of the, tangent of the angleto'which 'the filaments are being fed times the distance between the comb memberswherein the distance betweenthe I comb members is at least four times the diameter of the filament.

adjacent teeth is equal to at'least twice the diametefof a filament, a second combjmemb er spaced co-axially and laterally fromlthe' first comb' member a distance of" at least four times the diameter. of the filament andfdimen- Y "1 Referenees cit ed b y'lthje xam n -UNITED STAIES PATENI Sf 1,014,361- 1/12 Aumann 28-54 1,818,845 ,8/31 Fessl 57--138 1 ,958,598 -5/34 'Tre'bes 57--138' EARL M 'BERGERT; Primary x miner,

'OARL F. RAFFnEx minen.

, 8/57 Ritchie; s7 '13 

1. A POSITIONING COMB FOR ALIGNING AND SUPPLYING A PLURALITY OF MOVING FILAMENTS IN PARALLEL RELATION TO A SUBSEQUENT OPERATION WHEREIN EACH FILAMENT IS FED FROM A SOURCE CAPABLE OF PROVIDING AN INDETERMINATE LENGTH OF THE FILAMENT, THE COMBINATION COMPRISING; A FIRST COMB MEMBER INCLUDING A PLURALITY OF EQUALLY SPACED TEETH THEREALONG, THE SPACING BETWEEN EACH TOOTH BEING EQUAL TO AT LEAST TWICE THE DIAMETER OF THE FILAMENT, A SECOND COMB MEMBER DIMENSIONALLY SIMILAR TO THE FIRST MEMBER AND DISPOSED IN SPACED COAXIAL RELATION TO THE FIRST MEMBER AND POSITIONED TRANSVERSELY WITH RESPECT THERETO SO THAT THE TEETH OF THE FIRST COMB MEMBER ARE DISPLACED FROM THE TEETH OF THE SECOND COMB MEMBER A DISTANCE EQUAL TO THE PRODUCT OF THE TANGENT OF THE ANGLE TO WHICH THE FILAMENTS ARE BEING FED TIMES THE DISTANCE BETWEEN THE COMB MEMBERS WHEREIN THE DISTANCE BETWEEN THE COMB MEMBERS IS AT LEAST FOUR TIMES THE DIAMETER OF THE FILAMENT. 